// What the extraction does with one page, decided from the reader's own classification (ocr-service
// OCR3.15) and nothing the model says: whether the page is read at all, whether the model is shown the
// image besides the text, and which of the page's lines make up the text it is shown.
//
//   scan      the recognised text is a reading, not a record: image and text, the text marked as low trust
//   table     image and text: the grid is better read than recognised
//   text      text alone, unless the page is weak by the reader's own measure (isWeakPage)
//   drawing   left out by default: tens of thousands of characters of labels, no specification in them
//   empty     left out by default
//
// A class in `excluded` is never read, whatever the rule above; the deployment chooses the list.

import type { PageClass } from "../contract/index.js"
import type { ReadPage } from "./ports.js"
import { isWeakPage } from "./verify.js"

export type PagePlan =
  | { readonly kind: "skip" }
  | {
      readonly kind: "read"
      /** The model should be shown the page image besides the text. */
      readonly image: boolean
      /** The text is a recognition of an image and may be wrong: the prompt says so, and the image wins. */
      readonly lowTrustText: boolean
    }

export function planPage(page: ReadPage, excluded: readonly PageClass[]): PagePlan {
  if (excluded.includes(page.class)) return { kind: "skip" }
  switch (page.class) {
    case "scan":
      return { kind: "read", image: true, lowTrustText: true }
    case "table":
    case "drawing":
      return { kind: "read", image: true, lowTrustText: page.source === "ocr" }
    case "text":
      return { kind: "read", image: isWeakPage(page), lowTrustText: false }
    case "empty":
      return { kind: "read", image: false, lowTrustText: false }
  }
}

/**
 * The text of a page as the model is shown it: the lines in reading order without the ones the reader
 * flagged as repeating on most pages (a running header, a footer, a page stamp), which are the
 * document's furniture and not its content. A page the reader returned no lines for is its text as is.
 */
export function promptTextOf(page: ReadPage): string {
  if (page.lines.length === 0) return page.text
  return [...page.lines]
    .sort((a, b) => a.order - b.order)
    .filter((line) => !line.repeated)
    .map((line) => line.text)
    .join("\n")
}